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Energy bank to strengthen power supply of Rotterdam tram

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Energy bank’ to strengthen power supply of Rotterdam tram

Date

20 September 2023

Expertises

Sustainability, Power

Rotterdam’s public transport operator RET and consortium Energieverbinders (Dutch for Energy Connectors) have joined forces for a pilot that will lead to the realisation of the first Energy bank for the tram. The energy bank must be operational in December. The Energy bank will strengthen the power supply at the Posthumalaan turn loop, enabling RET to use the loop as a transfer point for passenger flows to Rotterdam Central Station and for soccer events.

When the Energy bank proves to be operating according to plan, the way will be open to solutions for more bottlenecks due to energy network congestion. The innovative power of Europe’s Rail Joint Undertaking, part of the EU’s Horizon Europe Programme (2020-2027) is used for the pilot.

RET built a tram turn loop at the Posthumalaan in Rotterdam a couple of years ago. This loop is currently used for calamities only. Once the power supply has been strengthened, the turn loop will also be suitable for tram traffic between the Kuip stadion and Wilhelminaplein metro station. Normally, an additional substation is necessary to strengthen the power supply, but that is costly, time consuming and wastes a lot of space.

Unplugged substation

The Energy bank is a good alternative for a substation. The concept was developed by consortium Energieverbinders (Dutch for Energy Connectors), consisting of Strukton Rail, Strukton Power and Hedgehog Applications. With modern technology and energy storage facilities, they developed a compact ‘unplugged substation’.

The Energy bank is identical to a classical rectifier station in terms of characteristics, but it is not connected to the electricity grid. The Energy bank charges itself through the catenary system of the tram at moments when no tram is passing (both during the day and at night) and makes sure that the energy is charged when electricity rates are low or even negative. This high-tech system serves as a fully operational extension of a classical power supply system with rectifier stations.

World first

The concept of the Energy bank only consisted on paper, until now. The Energy bank in Rotterdam is therefore a world first. Realising the Energy bank in practice will lead to two positive results:

  1. The Posthumalaan turn loop will have a full power supply, enabling regular use and use for events
  2. Practice-based insights will be gained as to applicability of the Energy bank as an alternative for the additional rectifier stations needed for planned improvements of the Rotterdam tram network to enable highly frequent traffic with faster trams

Characteristics

Characteristics of the Energy bank include:

  • It is a high-tech extension of the power supply with rectifier stations, and is therefore not affected by energy network congestion problems
  • It is fed through the catenary system, so no connection to the power grid is required
  • It weighs approximately 8,000-9,000 kg, so no foundation is required
  • It has small dimensions: 1.8 m deep) x 2.5 m high x ca 3 m long (depending on the power to be supplied) and can even be placed on a platform
  • It charges energy when electricity rates are low or negative
  • It is replaceable. When required, the Energy bank can easily be moved to a different place, to e.g. strengthen the power supply in case of detour routes
  • The price is lower than the price of a rectifier station. It has lower technical installation costs and no strengthening of the catenary system is required

Photo: Victor through Unsplash
On track to a sustainable future

SDG 7

This innovation contributes to Social Development Goal (SDG) 7 -Affordable and clean energy. Our current reliance on fossil fuels is unsustainable and harmful to the planet, which is why we have to change the way we produce and consume energy. Implementing these new energy solutions as fast as possible is essential to counter climate change, one of the biggest threats to our own survival. We actively wish to contribute to the United Nation’s SDGs, focusing on SDG 7, 8, 9, 12, 13, 15 en 17.

About Energieverbinders

Energieverbinders (Energy connectors) is a consortium of Strukton Rail Nederland, Strukton Power and Hedgehog Applications. They have joined forces to solve problems of energy network congestion with modern technology and energystorage facilities and, in so doing, accelerate the energy transition.

More information about the Energy Bank

To the Energy Bank innovation page

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Frequently asked questions

Find answers to frequently asked questions here.

What does sustainability mean in the rail and civil infrastructure sector?

Sustainability in rail and civil engineering focuses on reducing environmental impact across the entire lifecycle of infrastructure. This includes using emission‑free equipment, circular and recycled materials, and designing assets with a longer lifespan and lower maintenance requirements. Reusing structural components—such as circular viaduct beams or recycled copper contact wires for overhead lines—significantly reduces CO₂ emissions while conserving valuable raw materials.

How can CO₂ emissions be reduced in infrastructure projects?

CO₂‑reduction is achieved through a combination of clean construction methods and material innovation. Key strategies include:

  • Deploying zero‑emission machinery such as electric cranes, electric rail‑road vehicles (Krols), electric vans and battery‑powered locomotives.
  • Integrating circular concrete, geopolymer concrete, and recycled materials to lower embodied carbon.
  • Collaborating across the supply chain — from client to contractor to materials supplier — to scale circular and low‑carbon solutions.

These measures not only reduce carbon emissions but help create more resilient, future‑proof infrastructure.

Which sustainable innovations are being used in modern rail and civil engineering projects?

Infrastructure projects increasingly rely on advanced sustainable technologies, such as:

  • 100% recycled copper contact wire, reducing CO₂ emissions by up to 92%.
  • Geopolymer concrete, offering 50–80% CO₂ savings compared to traditional mixes.
  • Electric and battery‑powered locomotives for maintenance and logistics.
  • Circular overhead‑line foundations and poles made from low‑impact concrete.
  • The Energy Bank, an innovative click‑and‑go substation that captures and reuses regenerative braking energy.
  • Circular viaduct and bridge concepts, enabling reuse instead of demolition.

These innovations drive measurable environmental benefits throughout the asset lifecycle.

What is zero‑emission equipment in infrastructure construction?

Zero‑emission equipment refers to machinery that operates without producing exhaust gases, typically powered by electricity or batteries. Examples include:

  • Electric locomotives and battery locomotives
  • Electric cranes and rail‑road (Krol) vehicles
  • Electric vans and support vehicles

This equipment eliminates local emissions, improves air quality around work sites, reduces noise pollution and helps clients comply with increasingly strict sustainability requirements.

What does the future of sustainability in infrastructure look like?

By 2050, the infrastructure sector aims to be fully climate‑neutral. This future includes:

  • A robust, climate‑resilient infrastructure network designed for extreme weather.
  • A fully emission‑free construction fleet.
  • Circular material chains where components are reused at scale.
  • Rail as a leading sustainable mobility system, supported by smart energy management and low‑carbon construction methods.
  • Infrastructure that integrates nature, supports biodiversity and ensures safe mobility for everyone.

The transition is already underway, driven by innovation, collaboration and long‑term thinking.

Why is expanding the electricity grid essential for Europe’s energy transition?

Expanding the electricity grid is crucial to support increasing demand from renewable energy, electric mobility, gas‑free homes and growing data‑center capacity. A larger and stronger grid ensures reliability, prevents congestion and enables the seamless integration of solar, wind and other sustainable energy sources.

What civil engineering works are needed to build and upgrade energy networks?

Modern energy networks rely on extensive civil engineering works, including the construction of high‑voltage substations, transmission‑line foundations, access roads, cable routes and site preparation for electrical stations. These works form the physical backbone that allows grid operators to expand capacity safely and efficiently.

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